Hi,
Firstly, failover all redundancy groups to node 1.
user@srx> request chassis cluster failover redundancy-group 0 node 1
user@srx> request chassis cluster failover redundancy-group 1 node 1
Ensure Node 1 is handling all traffic first, then disable clustering on node 0.
user@srx> set chassis cluster cluster-id 0 node 0 reboot
Node 1 will be the primary on all RGs now and will be processing all traffic. Keeping node 1 in the cluster will make it easier to join node 0 again in the future.
If you disabled clustering on node 1, both will require a reboot upon rejoining.